Sheet materials such as sheets of tissue, towel, wet wipes, non-woven, air laid, meltblown, or spun-laced materials are frequently folded and superposed to form a stack which may be stored in a container or dispenser. Typically, all the sheets are equal in size when unfolded. It is desirable to interfold or interleave the sheets of the stack such that removing the first sheet from the container causes the next sheet to “pop-up” or move into position for removal. It is also desirable that the sheet folding configuration is stackable with a uniform height across its top surface. Therefore, it is desirable that any vertical cross section through the stack has substantially the same number of layers of sheet material.
A stack of sheet material is disclosed in U.S. Pat. No. 2,611,482, entitled Dispensing Package for Interfolded Sheet Material that issued Sep. 16, 1950, to Nelson. The stack is folded about a transverse fold axis and disposed into a container such that the stack or clip is dispensed from the side through the dispenser's opening as seen in FIG. 5. This arrangement of the sheet material in the stack allows for the use of a dispensing package having a relatively small base area, which reduces the foot print of the dispenser.
As discussed in the '482 patent: “From an inspection of FIGS. 6, 7 and 8 and the foregoing explanation, it will be seen that alternate withdrawals from the interfolded stack will start with a projecting sheet portion or leader as represented in FIG. 6 and that the intermediate withdrawals will be of a relatively loosely or freely supported sheet as represented by the sheet A in FIG. 8.
The described arrangement for withdrawing sheets is particularly adapted to the dispensing of fairly rough surfaced sheets which have a considerable amount of face-to-face frictional engagement with one another. Smoother sheets, such as typified by the better grades of soft, smooth facial tissues will be less effectively dispensed by the described arrangement owing to the relatively small amount of friction existing between the sheets, especially when the amount of material left in a package becomes small so that compression of the sheets within the package is greatly reduced.” Consequently, in the '482 patent, every other sheet withdrawal requires a higher level of pulling force and distance as compared to the intermediate sheet withdrawals of the loose or freely supported sheets. Additionally, the amount of the sheet material extending out of the dispensing package also varies between the sheets as they are dispensed.
An ongoing desire in the packaging of sheet materials is to offer alternative packaging formats and to offer these formats on smoother sheet materials such as facial tissue. Therefore, what is needed is an improved stack of interfolded sheet materials specifically configured for side dispensing that improves sheet dispensing by eliminating intermediate withdrawals of a relatively loose or a freely supported sheet, and/or that reduces the pulling force variation, and/or that provides for a consistent amount of sheet material extending out of the dispenser. Also, what is needed is an interfolded stack that effectively dispenses any type of sheet material, wet or dry, including lower coefficient of friction or smoother sheet materials.